US20180072623A1 - Retarding mixture for alkali-activated binding agents - Google Patents

Retarding mixture for alkali-activated binding agents Download PDF

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US20180072623A1
US20180072623A1 US15/552,928 US201615552928A US2018072623A1 US 20180072623 A1 US20180072623 A1 US 20180072623A1 US 201615552928 A US201615552928 A US 201615552928A US 2018072623 A1 US2018072623 A1 US 2018072623A1
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alkali
binding agent
hydrogen carbonate
acid
activated binding
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Peter Blaum
Frank Bullerjahn
Macie J Zajac
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Heidelberg Materials AG
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HeidelbergCement AG
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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/006—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing mineral polymers, e.g. geopolymers of the Davidovits type
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B22/00—Use of inorganic materials as active ingredients for mortars, concrete or artificial stone, e.g. accelerators, shrinkage compensating agents
    • C04B22/08—Acids or salts thereof
    • C04B22/10—Acids or salts thereof containing carbon in the anion
    • C04B22/106—Bicarbonates
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B24/00—Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
    • C04B24/04—Carboxylic acids; Salts, anhydrides or esters thereof
    • C04B24/06—Carboxylic acids; Salts, anhydrides or esters thereof containing hydroxy groups
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
    • C04B28/021—Ash cements, e.g. fly ash cements ; Cements based on incineration residues, e.g. alkali-activated slags from waste incineration ; Kiln dust cements
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
    • C04B28/04—Portland cements
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
    • C04B28/08—Slag cements
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/18—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing mixtures of the silica-lime type
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/24—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing alkyl, ammonium or metal silicates; containing silica sols
    • C04B28/26—Silicates of the alkali metals
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
    • C04B40/0028—Aspects relating to the mixing step of the mortar preparation
    • C04B40/0039—Premixtures of ingredients
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
    • C04B2103/20—Retarders
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
    • C04B2103/30—Water reducers, plasticisers, air-entrainers, flow improvers
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/10—Compositions or ingredients thereof characterised by the absence or the very low content of a specific material
    • C04B2111/1062—Halogen free or very low halogen-content materials
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/20—Resistance against chemical, physical or biological attack
    • C04B2111/21—Efflorescence resistance
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P40/00—Technologies relating to the processing of minerals
    • Y02P40/10—Production of cement, e.g. improving or optimising the production methods; Cement grinding
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies
    • Y02W30/91—Use of waste materials as fillers for mortars or concrete

Definitions

  • the present invention relates to retarding mixtures which delay the setting and/or hardening of alkali-activated inorganic binding agents, in particular geopolymers.
  • Geopolymer designates inorganic binding agents that, analogously to classic Portland cement, can be mixed to a pourable paste and then harden to solid structures.
  • the hardening in classic geopolymers that form zeolite-like structures takes place by means of a reaction of a silicate with an aluminate under strongly alkaline conditions.
  • these conditions can be provided by a combination of an alkali metal hydroxide solution and an alkali metal silicate solution, wherein an aqueous binding agent system emerges.
  • a dry binding agent system can be produced by a solid activator being used, for example a solid alkali metal silicate.
  • the result of the reaction of the geopolymer is an amorphous, three-dimensional network of silicon and aluminium atoms that are crosslinked by oxygen atoms to a polymer structure.
  • raw materials are used which provide silicates and aluminates in suitable quantities.
  • mineral raw materials e.g. metakaolin
  • synthetic materials such as industrial by-products, e.g. silicon-rich fly ash
  • industrial by-products e.g. silicon-rich fly ash
  • the use of industrial by-products is preferred to the use of mineral raw materials.
  • the spectrum of the raw materials/industrial by-products used for the production of the kind of binding agent previously mentioned has gradually expanded.
  • pozzolanically active, silicon-rich fly ash, latent hydraulic and/or pozzolanically active, calcium-rich fly ash and granulated blast furnace slag/slag are thus used.
  • a high proportion of the glass phase by volume is advantageous for the reactivity of the binding agent since the glass phase has high solubility.
  • the reactivity is determined by the chemical composition: the higher the CaO content, the higher the reactivity.
  • materials with a high free lime content should be avoided since free lime can cause flash setting.
  • Carbon compounds in the form of unburnt coal particles increase the required amount of an activator and the water demand because of their large internal surface, which worsens the performance of the binding agent and increases the costs.
  • the reactive surface is a further important influencing variable, the higher the reactive surface, the more soluble the raw material.
  • the use of ground raw materials containing aluminosilicates is advantageous, which has a greater impact with fly ash than with granulated blast furnace slag. Typical values for said properties with common raw materials are compiled in the following table 1:
  • the activator should provide a high pH value in order to be able to dissolve the raw materials used of a glassy crystalline nature (e.g. fly ash, granulated blast furnace slag). In doing so, the chemical bonds in the present aluminosilicate, calcium silicate, calcium aluminosilicate, calcium aluminate, calcium ferrite, and calcium aluminoferrite compounds are broken up, and the monomer and polymer fragments released are supplied to the pore solution. Furthermore, the activator supplies silicon and aluminium oxide compounds, which facilitate the formation of the geopolymer network. Different substances are suitable as the activator for geopolymers:
  • Alkaline/alkaline earth silicates e.g. sodium or potassium silicate, sodium metasilicate, both anhydrous and pentahydrate
  • Alkaline/alkaline earth hydroxides e.g. sodium hydroxide, calcium hydroxide, potassium hydroxide
  • Alkaline/alkaline earth carbonates e.g. sodium carbonate
  • Alkaline/alkaline earth sulphates e.g. sodium sulphate, potassium sulphate
  • the alkaline activator can be added as a liquid or solid component.
  • the activator When adding in a solid state, the activator is preferably ground together with the latent hydraulic and/or pozzolanically active binding agent components in order to increase the reactivity.
  • the co-grinding can be initiated during the ongoing grinding process of the previously mentioned latent hydraulic and/or pozzolanically active binding agent components. If these are already present in a ground or sufficiently fine form, an additional grinding step can be carried out in order to be able to guarantee an adequately homogeneous distribution of the activator, respective equal wetting of the reactive surfaces of the raw material. Liquid activator components are prone to carbonating, thus they have to be stored in a sealed manner. Depending on the activator components, different pH values are obtained, the following table 2 gives an overview.
  • the hardening of geopolymers can be divided into three phases.
  • silicates, aluminates and ferrites are released by breaking up the chemical bonds from the present glassy crystalline binding agent components/raw materials. This is initiated by hydroxide ions from the activator. Thus, monomolecular and condensed fragments are introduced into the pore solution.
  • the release requires very strong alkalis, or weaker alkaline substances suffice.
  • strong activators are necessary for geopolymers that consist predominantly of aluminosilicate, i.e. network forming aluminium and silicon oxides, since many covalent bonds are present.
  • aluminosilicate structures are modified by a substantial content of foreign ions such as Ca 2+ , Mg 2+ , Na + , K + in the glass phase, many ionic bonds are present that can also be broken by weaker activators.
  • Silicon-rich fly ash consequently requires strong activators, such as alkaline hydroxides and alkaline silicates; weaker activators such as carbonates are often sufficient for lime-rich fly ash and granulated slag.
  • the condensation takes place in which the solid three-dimensional network of aluminosilicates is formed.
  • mono and polysilicate ions from the activator can aid the reorganisation of the aluminosilicate fragments from the geopolymer to solid structures with a higher degree of polymerisation.
  • hydration processes are also initiated analogously to Portland cement.
  • CaO calcium silicate hydrates
  • CaA-S—H calcium aluminate silicate hydrates
  • metal metal hydroxide e.g. representatives of the hydrotalcite group
  • Ca metal hydroxides e.g. representatives of calcium aluminate hydrates
  • the presence of calcium contributes to the mechanical strength of the hardened binding agent system, not only by forming C—S—H and C-A-S—H, but also by accelerating the geopolymer hardening.
  • the reaction of the geopolymers can also be accelerated by heating to up to 90° C.
  • the composition of the geopolymer binding agent has to take different parameters into account and can thus be complicated.
  • the most important parameters are the CaO content, the content of activator and the SiO 2 /Na 2 O ratio in the activator. Furthermore, the water/binding agent value and the hardening temperature exert an important influence.
  • Silicon-rich fly ashes with a low content of CaO result in classic geopolymer binding agents that substantially only harden by forming aluminosilicate networks (zeolites).
  • strongly alkaline activators are used.
  • the CaO content increases to >10%, such as when using latent hydraulically active calcium-rich fly ash or granulated blast furnace slag, for example, during the hardening, the formation of C—S—H, for example, is added to the polymerisation process.
  • an SiO 2 /Na 2 O ratio in the activator of 0.75 to 1.0 and a water-binding agent value of about 0.35 are suitable.
  • the strength that is able to be obtained increases in these binding agents with an increasing CaO content.
  • the CaO content also strongly influences the open time of the binding agent. With an increasing CaO content, the open time reduces so much that processing is no longer possible. Thus, for such geopolymer binding agents, retarding admixtures are necessary.
  • the activator In geopolymer binding agents with a CaO content from 10 wt %, as they are obtained, for example, with granulated blast furnace slag as the raw material, the activator has to be individually adjusted to the specific system.
  • geopolymers with CaO contents in the lower range of ⁇ 10% require somewhat larger amounts of activator; with a CaO content of >10 wt %, optimal strengths mostly arise having lower contents of activator.
  • admixtures means those substances that are added to specifically change/adjust properties of the binding agent while processing or of the hardened system.
  • examples for admixtures include concrete admixtures according to DIN EN 934 and those with technical approval, for example: concrete liquefiers, plasticizers, air-entraining agents, sealants, retarders, setting accelerators, hardening accelerators, stabilisers etc.
  • Activators are not included, although these are used as admixtures in OPC based systems; in the geopolymers, the activators are a component of the binding agent.
  • the additives used in concrete in order to specifically improve or obtain properties such as rock flours (filler), pigments, fibres etc., have to be distinguished from the admixtures.
  • admixtures in the alkali-activated binding agent systems has to take several specific features of these systems into account. Firstly, even the small amount of water introduced with the admixture has to be taken into consideration for the W/B since the binding agent is very sensitive to this.
  • the possible content of carbon compounds in the form of unburnt coal particles, in particular in systems made of fly ash, can drastically influence the dosing of the admixture, since admixtures are typically organic substances that are preferably connected on the inner surfaces of the non-reactive coal particles that are dominant in terms of area. Furthermore, it must be ensured that an impact is not based on effects such as entrapped air.
  • boric compounds, lignosulphates, sodium gluconate, sodium glucoheptonate, tartaric acid and phosphorous compounds are deemed effective as retarders in geopolymer cement.
  • these two applications are concerned with a very specific use, namely mixtures for oil drilling uses capable of pumping in which the requirements for processability, strength development and final strength deviate greatly from those in building construction and in other sectors.
  • a particularly crucial difference is the increased temperature during use and hardening.
  • boric compounds, lignosulphate and phosphorous compounds are tested, but only for boric compounds the strength is also determined. This decreases in comparison to the systems that are not delayed.
  • the above object is thus solved by a retarding mixture comprising sodium gluconate and alkali hydrogen carbonate, by an alkali-activated binding agent containing sodium gluconate and alkali hydrogen carbonate, and by a method for adjusting the solidification properties in which sodium gluconate and alkali hydrogen carbonate are added to an alkali-activated binding agent.
  • alkali-activated binding agents shall include both classic geopolymers and mixtures which comprise aluminosilicates or aluminates and silicates and/or calcium (alumino)silicates in combination with an activator and at least also harden by forming three-dimensional crosslinked aluminosilicate polymers, calcium silicate hydrates (C—S—H), calcium aluminate silicate hydrates (C-A-S—H), metal hydroxides (e.g. representatives of the hydrotalcite group) and Ca metal hydroxides (e.g. representatives of the calcium aluminate hydrates).
  • C—S—H calcium silicate hydrates
  • C-A-S—H calcium aluminate silicate hydrates
  • metal hydroxides e.g. representatives of the hydrotalcite group
  • Ca metal hydroxides e.g. representatives of the calcium aluminate hydrates
  • Alkali-activated binding agents with low CaO contents means CaO contents of up to 10 wt % in terms of the total content of reactive CaO in the underlying binding agent system; alkali-activated binding agents with average to high CaO contents are those with >10 wt % CaO, preferably >15 wt % and more CaO.
  • fly ash that can be both calcium rich and silicate rich, granulated blast furnace slag and slag are used as raw materials for the production of alkali-activated binding agents.
  • mixtures are used such that a desired content of aluminium oxide, silicon dioxide and other parameters such as the ratio Si/Al, (Si+Al)/Ca etc. are obtained.
  • the raw materials can be pretreated, for example, in order to remove carbon and other organic components.
  • a thermal or hydrothermal treatment can also take place in which, for example, a conversion from unreactive crystalline phases into amorphous phases takes place.
  • Fly ashes or dusts from cement production can already be present at the desired level of fineness. If the raw materials are not present at the desired level of fineness, grinding takes place in a known manner. If raw materials are to be mixed, this can often take place advantageously by means of common grinding. When grinding, conventional devices can be used. Depending on the grindability, grinding aids such as triisopropanolamine (TIPA) or triethanolamine (TEA) are preferably used.
  • TIPA triisopropanolamine
  • TAA triethanolamine
  • the inherently known substances are used as activators. As described above, these are, above all, silicates, hydroxides, carbonates, sulphates and Portland cement or Portland cement clinker and corresponding combinations of the activators previously mentioned.
  • Sodium silicate, potassium silicate, anhydrous sodium metasilicate and sodium metasilicate pentahydrate are preferably used as silicates.
  • Alkaline and alkaline-earth hydroxides and oxides that react to hydroxides when in contact with water are suitable as the hydroxide.
  • Sodium, potassium and calcium hydroxide are particularly preferred.
  • Sodium carbonate is preferably used as the carbonate.
  • Sodium sulphate and potassium sulphate are suitable as sulphates.
  • Portland cement or Portland cement clinker can also be used in the form of waste fractions from the production of Portland cement, such as process meals and dusts.
  • activator or activators is adjusted to the latent hydraulically and/or pozzolanically active binding agent components/raw materials in an inherently known manner. Usual amounts range from 10 to 20 wt % in terms of the solid content of the binding agent. It should be noted that if using Portland cement (clinker) as an activator, in comparison to Portland composite cement and Portland pozzolan cement, less Portland cement (clinker) is used.
  • dry activators can be advantageously mixed when grinding or can be ground separately.
  • Dissolved activators are expediently added to the mixing water; however they can also be added before or after this.
  • the binding agent Depending on the binding agent, the addition of water takes place, above all, for adjusting the flowability and for providing the medium for restructuring the aluminosilicates, aluminates and silicates; with binding agents with a high CaO content, this is also for enabling hydraulic hardening.
  • the binding agent is based on the sum of the aluminosilicates, aluminates, silicates and the solid content of the activators; with water, along with the water connected in the activator, also water optionally introduced for dissolving the activator and/or admixture is taken into account.
  • W/B ranging from 0.2 to 0.5 are useful, in particular 0.3 to 0.45, especially from 0.35 to 0.40.
  • the fineness of the solid binding agent components according to Blaine typically ranges from 3000 to 5000 cm 2 /g, in particular at around 4000 cm 2 /g. Higher fineness leads to an increased reactivity up to a certain limit, but also requires higher grinding energy and more water such that a useful compromise is chosen in an inherently known manner for the respective binding agent and its application.
  • the binding agent contains the retarding mixture according to the invention comprising sodium gluconate and alkali hydrogen carbonate for adjusting the open time and thus ensuring a useful processability.
  • the retarding mixture comprising sodium gluconate and alkali hydrogen carbonate for adjusting the open time and thus ensuring a useful processability.
  • sodium or potassium hydrogen carbonate are used as the alkali hydrogen carbonate.
  • the amount preferably ranges from 0.1 to 10 wt % with respect to the binding agent, particularly preferred from 0.5 to 5 wt % and most preferably from 1 to 3 wt %.
  • the ratio of sodium gluconate to alkali hydrogen carbonate preferably ranges from 9:1 to 1:4, especially at around 3:1 to 1:1.
  • the retarding mixture according to the invention can be used in the preferred dosing and mixing ratio in both a dissolved and a solid state as components of the binding agent or concrete admixtures.
  • a binding agent component the retarding mixture according to the invention is here mixed in to the binding agent as a further component, preferably in a solid state, or, as part of the required grinding processes, is ground together with the binding agent components.
  • the retarding mixture according to the invention can be used in both a dissolved and solid state in the preferred dosing and mixing ratio.
  • the retarding mixture is here preferably added to the mixing water.
  • the time point be chosen freely here, but preferably takes place during the mixing process of the binding agent, aggregate and mixing water.
  • the addition preferably takes place in such a manner that a homogeneous distribution of the admixtures in the concrete mixture is ensured; this can take place in individual dosing steps or as a continuous process during the time period of the addition of the mixing water.
  • the retarding mixture according to the invention in dry form is preferably incorporated in after adding the binding agent components.
  • the retarding mixture according to the invention delays the setting of alkali-activated binding agent systems, in particular of geopolymers that have an average to high CaO content in terms of the solid content of the binding agent, and, in particular in pH ranges above the effectiveness limit of known admixtures. Delaying the setting of the binding agent in concrete and cement mortar leads to a significant lengthening of processing times and thus also of possible transport times. Furthermore, the retarding system is free from chlorides and does not cause any efflorescence. It is suitable as the setting retarder for construction site concrete, transport concrete and pump concrete, for screed and cement mortar and for large monolithic components (e.g. pre-cast uses).
  • the invention is advantageous, in particular, for binding agents with a high CaO content and significantly alkaline activators.
  • the retarder according to the invention clearly increases the open time without impairing the compressive strength. In some cases, the compressive strength even increases. Particularly advantageous is that the effect increases at higher pH values. Furthermore, a plasticising effect also occurs, by means of which the processability is improved. From an economical point of view, it is noted that the retarder according to the invention is more cost-effective than many other proposals.
  • the invention also relates to all combinations of preferred embodiments, unless these are mutually exclusive.
  • the specifications “about” or “approx.” in connection with a numerical figure mean that values that are higher or lower by 10%, values that are higher or lower by 5% and in any case values that are higher or lower by 1% are included.
  • An alkali-activated binding agent comprising 64 wt % fly ash 1, 21 wt % granulated blast furnace slag 1 and 15 wt % activator with regard to the solid content of the binding agent was produced by mixing the aforementioned components.
  • the SiO 2 /Na 2 O ratio in the activator solution consisting of a 40% NaOH solution and a commercial water glass by the company PQ (product name: “C0265”) in the mixing ratio of about 1:1.7, here amounted to 1.0.
  • fly ash 1 was here ground down to a fineness of 2850 cm 2 /g, granulated blast furnace slag to a fineness of 4920 cm 2 /g.
  • the chemical composition of fly ash 1 and granulated blast furnace slag 1 is stated in Table 3.
  • a CaO content of 15.1 wt % in terms of the solid content of the binding agent results.
  • the numbering of the effects observed obviously includes a subjective, personal component, however, from experience that becomes fairly uniform with increasing practice.
  • the numbering enables the comparison of samples by tabular and graphic depiction.
  • the depiction in curves provides an additional plausibility check.
  • the method is particularly well suited to the relative assessment of solidification processes before and during the setting of binding agents as part of series samples that are changed systematically and in steps. It presents a meaningful precursor to standard tests in which the effect tendency of certain additives or binding agent mixtures, where necessary also by means of a large number of individual attempts, can be seen while using small amounts of material.
  • the time t ini up to a slight but noticeable stiffening (leathery) was determined.
  • the binding agent of example 1 and an analogously composed binding agent with fly ash 2 were mixed with 1% of different retarders and, as in example 1, the time until the noticeable stiffening of the paste samples was determined. Furthermore, as described in [00019], mortar prisms were produced and, in addition, the compressive strength was measured after 28 days (stored at 20° C., 100% rel. air humidity). Table 5 summarises the results.
  • FIG. 1 a shows the spreading capacity measured in mortar samples according to DIN/EN1015-3
  • FIG. 1 b shows the compressive strength measured in mortar samples according to DIN/EN 1015-11.
  • the chemical composition of fly ash 3 and granulated blast furnace slag 2 is stated in Table 3.
  • the W/B was set to 0.40 for all mortar mixtures.
  • the spreading capacity already significantly decreases after 30-45 min with significantly increased CaO content of >10.0 wt %, accompanied by a clear stiffening of the samples.
  • the open time reduces to such an extent that a processing is no longer possible.
  • retarding admixtures are necessary.
  • FIG. 2 clarifies the ambivalent character of variable CaO contents already described in [00020]. While the binding agent “FA3/S2” described in [00060] with a low CaO content of ⁇ 10 wt % indeed showed a good processability, though a poor strength development, with the binding agent systems based on fly ash/granulated blast furnace slag, “FA3/S2” with a significantly higher CaO content>10 wt %, a poorer processability in the sense of a very short open time was generally associated with high strengths.

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US15/552,928 2015-03-17 2016-03-14 Retarding mixture for alkali-activated binding agents Abandoned US20180072623A1 (en)

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WO2019110134A1 (en) 2017-12-08 2019-06-13 Ecocem Materials Limited Ground granulated blast furnace slag based binder, dry and wet formulations made therefrom and their preparation methods
EP3597614A1 (de) * 2018-07-17 2020-01-22 HeidelbergCement AG Neues verzögerungssystem für csa-basierte zemente
CN109020293A (zh) * 2018-09-18 2018-12-18 济南大学 一种超支化型缓凝剂的制备及应用
AU2021234863A1 (en) * 2020-03-13 2022-10-06 Sika Technology Ag Slag-based hydraulic binder, dry mortar composition comprising same and system for activating a slag-based binder
CN112266070A (zh) * 2020-09-16 2021-01-26 中国神华能源股份有限公司国华电力分公司 一种脱硫废水中重金属钝化处理方法及装置
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CN116421923A (zh) * 2023-04-12 2023-07-14 江阴市月城昇利生物科技有限公司 焚烧飞灰处理葡庚复合液的制备方法

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CN111039683B (zh) * 2019-12-30 2022-08-09 长兴兴鹰新型耐火建材有限公司 一种用于垃圾焚烧窑的抗硫碱耐腐蚀耐磨浇注料及其制备工艺

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